networkZONE Products for the week of December 18, 2006
Metalink Says…
Consumer Electronics Grade 802.11n-Draft Compliant Dual-Band Chipset Enables Wireless Digital Entertainment Throughout the Home
Metalink Ltd. has unveiled the second generation of its industry-leading WLANPlus chip-set, the industry's first consumer electronics (CE)-grade, 802.11n-draft-compliant dual-band chip-set. Designed to enable high-throughput, rich-content, quality-critical applications, WLANPlus provides the foundation for a robust, full-coverage wireless home entertainment network.
Commenting on the news, Metalink's Vice President of Wireless LAN Marketing, Barry Volinskey, said, "We are proud to offer the industry's first CE-grade chip-set which is fully compliant with the 802.11n standard draft. During the past year, we have successfully integrated our first-generation WLANPlus into a broad range of new 'connected' home entertainment products of leading CE vendors, and have received very enthusiastic feedback. Our second-generation chipset was meticulously characterized to accommodate the different needs of the CE market and to deliver a worldwide first-class solution for the WLAN digital home environment. We expect that the availability of this advanced second-generation product will strengthen our market leadership in the wireless digital home entertainment space."
Metalink's WLANPlus 802.11n chip-set family is optimized to go beyond previous solutions that are designed primarily to transport data, and addresses the far more rigorous needs of the consumer electronics market. As such, it supports the most demanding optional specifications of the 802.11n standard with functionality that is critical for the streaming of high-quality High-Definition Television (HDTV) video throughout the home (three MPEG2 HDTV streams at 60Mbits/s with whole-home coverage at 60 feet). First-generation WLANPlus technology has already been integrated by leading CE manufacturers into a broad range of products, including Residential Gateways, Digital Televisions, HDTVs, Set-Top Boxes (STB), Media Adaptors and Digital Video Recorders (DVR).
Metalink's second-generation WLANPlus chip-set presents the cutting-edge technology of CE-grade requirements for wireless home networks, supporting both 2.4GHz and 5GHz. In line with the specifications of IEEE drafts for 802.11n Wi-Fi certification, it is fully compliant with 802.11a/b/g-based legacy devices, as well as 802.11h (radar detection), 802.11i (security) and 802.11e Quality of Service (QoS). The new chip-set supports optional standard features as well as proprietary algorithms to meet the critical demands required for sensitive multimedia applications that require superior bandwidth and the lowest possible jitter, latency and packet loss.
To double network coverage in a home environment, second-generation WLANPlus solution also features a Maximum Likelihood (ML) slicer and an advance-coding gain using Low Density Parity Check (LDPC) technology. In a 2x3 Multiple-Input Multiple-Output (MIMO) rank, the ML slicer provides benefits equivalent to those of Transmit Beam Forming, only without the pendency problems associated with the latter since it is implemented within the digital signal processing portion of the transmitter. To guarantee QoS and optimize home performance, WLANPlus also features sophisticated QoS mechanisms, such as Enhanced Distribution Channel Access (EDCA) with Admission Control and Fast Link Adaptation (FLA). Dynamic Link Adaptation (DLS) cuts by 50 percent the amount of airtime that must be used for QoS operations, and significantly increases network efficiency.
The second-generation WLANPlus chip-set includes full implementation of an integrated Media Access Controller (MAC), dramatically reducing the required processing power and memory allocation from the application host processor. This simplifies WLANPlus integration with consumer electronics devices and reduces the total product cost. The transition to the new chip-set is transparent to the customer due to an agnostic driver's implementation.
"Wi-Fi chip-sets for media adapters and line-powered and portable consumer electronics will increase by a factor of 5 from about 23 million shipments in 2005 to nearly 110 million in 2008," stated Philip Solis, senior analyst at ABI Research. "Consumer electronics is one of the largest growth segments for Wi-Fi enabled chip-sets. Among wireless solutions, there are many that will compete for in-room wireless connectivity, but Wi-Fi is necessary to stream video wirelessly across the home."
Metalink offers several reference designs along with the new chip-set, including Mini PCI (type IIIB), CardBus and Residential Gateways.
About WLANPlus
The WLANPlus family consists of the company's MtW8171 baseband device and the MtW8151 radio frequency integrated circuit (RFIC). A combination of features enables Metalink's WLANPlus family to deliver multiple HDTV streams to any location within a radius of 100 feet, while maintaining full QoS performance. Innovative packet-aggregation techniques boost MAC efficiency with double the effective throughput of other solutions. The inclusion of 2x3 real MIMO technology further improves throughput and QoS, and the use of sophisticated channel-bonding and antenna-loading techniques in the 5 GHz frequency band provide critical additional video-distribution performance.
The WLANPlus chipset also includes a full implementation of an integrated lower and upper MAC, reducing dramatically the required processing power and memory allocation from the host application processor. This simplifies the integration with consumer electronics devices and reduces the total product cost. Additionally, advanced LDPC forward error-correction (FEC) coding significantly boosts coverage range and signal robustness as compared to previous approaches. The chip-set also fully supports 802.11i security features and the 802.11e QoS standard, both of which are critical for high-priority voice and video services.
EN-Genius Network Says . . .
Despite any reservations I may have on the practicality (or desirability) of using 802.11n to stream wireless multimedia through homes, if any chip set on the market can do it, it's probably Metalink's WLANPlus chip set. When Metalink decided to expand its product line beyond their robust DSL chip sets I was dubious about such a small company taking such a large diversion. But after looking at their chip set it seems that they have been able to apply much of what they learned jamming 100 Mbit/s down crummy twisted pair wires to the challenges of moving 80 Mbit/s of actual video payload (which requires around 160 Mbit/s of raw bandwidth) at distances of 100 ft through up to 5 layers of walls and ceilings.
The chip set seems to be nicely-designed, with functionality that's been properly segmented between a radio chip (MtW8151) and a baseband/MAC device (MtW8171) (see Fig. 1) instead of the conventional single-chip approach favored by most big-name manufacturers. Although it is capable of 2.4-GHz operation, Metalink says that their design team concentrated specifically on enhancing its performance in the 5-GHz band. This also explains why they only used a CMOS process for their baseband/MAC and fabricated their RF chip in SiGe, a process whose higher ft and lower intrinsic noise is much better suited for operation in the 5-GHz band.
 Metalink's MtW8151 radio is a multi-channel zero-IF transceiver that's been specifically designed for MIMO operation. It includes two complete dual-band transmit chains that feed external PAs. The three dual-band receive chains are coupled to their own integrated LNAs. I had some concerns about substrate noise, coupled RF and other low-level signal gremlins that can mess with the noise floor, or even the linearity, of a receive chain. Metalink was stingy on technical details but assured me that their proprietary isolation techniques allows them to deliver performance that's comparable to a receiver using external LNAs. With so little to go on, I can't verify or disprove Metalink's claims but will take their word (at least for the moment) based on the good performance of their VDSL analog front ends. Of course, I'd welcome any insights that some of our knowledgeable readers might supply about this.
But despite the fact that Metalink's radio seems to be one of the nicer designs I've seen of late, they claim that the real secret sauce that makes their chip set unique lies in the digital half of their product. The baseband/MAC chip integrates an AFE, a MIMO transceiver, a hardware 802.11 MAC, a MIPS controller and host interfaces. It also contains an 802.11n (draft)-compliant low-density parity check (LDPC) FEC engine which Metalink says adds around 20% to the system's range.
Besides extending the radio's range, the LDPC error correction helps support the transceiver's packet-burst mode for greater throughput. Formally known as packet aggregation with block acknowledgement, this 802.11n-compliant option concatenates up to 32 packets in a single block that cuts through tons of protocol overhead that would normally eat up the channel bandwidth with a handshake between each packet transfer. While not appropriate for all kinds of file transfers, packet bursting is great for voice or video streams which can tolerate at least some level of packet loss. When combined with error correction, you get a wireless link that can keep packet errors low enough to support packet bursting over much longer distances and under more challenging conditions. Throughput is further enhanced using n-compliant channel bonding which allows the chip set to more than double its single-channel data rate.
As I mentioned earlier, the baseband's MIMO receiver uses several hardwired DSP elements adapted from Metalink's 100 Mbit/s VDSL technologies. One of the chip's more interesting DSP-based elements is a near maximum likelihood (NML) slicer that helps locate and align the amplitude component of the digital OFDM constellation with respect to where it should be in the analog realm. Between the fact that Metalink did not give me all the details of its operation and not having seen it running, I can't vouch for how well this works but, from what I understand of its operation, it should help extend range and give the receiver a distinct performance advantage in marginal channel conditions.
Since the transceiver is primarily intended for transmitting high-quality digital video and other delay-sensitive streams, Metalink's smart MAC supports all of the checkbox options in the 802.11n standard that are aimed at improving video capacity and performance. This includes the EDCA-AC option that provides priority queuing for video while maintaining strict QoS parameters for VoIP.
The end result is a chip set that really appears to be well-suited to wireless media distribution at HDTV-capable bit rates over useful distances. But is Metalink really the first company to do this? If you were to take their press release as gospel, that would certainly be the case. In reality, it's more complicated than this since several companies already claim they are capable of supporting HD-video streams over the 5-GHz band. When I pointed this out, Metalink clarified their definition of first as being the only 5-GHz MIMO-capable, video-specific product that uses channel bonding, LDPC FEC, spatial diversity, and packet aggregation.
With those criteria in mind, I took a quick survey of Metalink's competition, i.e .Airgo, Atheros, Broadcom, and Marvell to see how they stacked up. While I could only put in a couple of hours' research into the project and couldn't produce any definitive answers, the results I did provide should serve as a useful first-order rough guide to help you in your own more detailed research. Here's what I found:
Airgo
Airgo (recently acquired by Qualcomm) has a spatially-diverse MIMO chipset but, from the sketchy information on their web site, they do not appear to have any special features to support video. Their specification includes a 40-MHz channel-bonded mode which indicates they support 802.11n operation at 5 GHz, although Metalink disputes this.
Atheros
Atheros' AR5008 and related chipsets are advertised to run with a AR5133 3x3 MIMO radio that has three integrated single-band 2.4/5-GHz radios which the company claims can support 5, 10, 20 and 40 MHz channels. The sketchy public data sheet for the chip set indicates that they support some sort of FEC (probably LDBC) and channel bonding but looks like their XSPAN 40 MHz double channel scheme is proprietary and not 802.11 compliant. I could not find any mention of packet aggregation or other performance enhancements that Metalink employs in the literature, but you should double-check with Atheros about this as I may have missed something.
I wish I could give you a better comparison, but recent changes in Atheros management and the public relations agency that they use has weakened my contacts with them and I have not been briefed on this product. This means I cannot verify or dispute their claims with any authority other than my past history with them and knowledge of their previous products. In this regard I would say that, while Atheros has produced some excellent products of late, they are sometimes prone to overly-optimistic promises for performance and functionality.
Broadcom
While I have had good working relationships with many of Broadcom's other product groups, their wireless group has been downright evasive about discussing the technical details of their products with me. This forced me to rely on the spec sheet on their Dual-band BCM4704/05 chip set for most of my information. Broadcom's literature says that the BCM4704 works with most of their 2.4 and/or 5 GHz IntensiFi radios and accommodates 2X2, 3X3 and 4A-4 antenna configurations using their BCM2055 dual-band radio. Unfortunately, I could not locate any details on their web site that could give me confidence they are shipping working 802.11n radios capable of supporting useful streaming video at 5 GHz. The reference designs I found were for 2 x 2 configurations that supported a maximum of 300 Mbit/s and appeared to be data-oriented, with few if any specialized mechanisms to support video. Hopefully, Broadcom's wireless group will help me get you a better picture of what they can actually deliver in a briefing for their next product announcement.
Marvell
Marvell says that their TopDog 802.11n radio can support both the 2.4-GHz and the 5-GHz bands, as well as 20-MHz and 40-MHz channels, but they have never given me a decent briefing on this product line (despite repeated requests) and there is nothing I can find on their site that gives me enough details about their radios to refute Metalink's assertions that their chip set only supports 802.11n in the 2.4-GHz band.
Based on the sketchy information I was able to obtain from the above manufacturers, it looks to me like Metalink is not the first to offer a 5-GHz video-capable link, and several chips at least pay lip service to support for several of the video-critical 802.11n options. So while it's arguable as to whether they have a bona fide industry first here, the architectural features and functionality this chip set appears to support makes it a top contender in this class of application.
Samples of Metalink's MtW8151 and MtW8171 are available now, with production scheduled for April/May of 2007. High volume pricing for the WLANPlus chip set will be in the sub-$20 range.
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